Rab14 regulates maturation of macrophage phagosomes containing the fungal pathogen Candida albicans and outcome of the host-pathogen interaction.
Bottom Line: The duration of Rab14 retention on phagosomes was prolonged for hyphal cargo and was directly proportional to hyphal length.However, Rab14 depletion delayed the acquisition of the late phagosome maturation markers LAMP1 and lysosomal cathepsin, indicating delayed formation of a fully bioactive lysosome.Therefore, Rab14 activity promotes phagosome maturation during C. albicans infection but is dysregulated on the phagosome in the presence of the invasive hyphal form, which favors fungal survival and escape.
Affiliation: Aberdeen Fungal Group, University of Aberdeen, Aberdeen, United Kingdom.Show MeSH
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Mentions: Rab14 associates with phagosomes transiently, and we hypothesize that this association may be important in the regulation of phagolysosome biogenesis. To further understand the role of Rab14, we investigated whether markers of early and late stages of the phagosome maturation process were affected in macrophages with reduced Rab14 expression. RAW 264.7 macrophages depleted of Rab14 (using siRNA) were cotransfected with eGFP-Rab5 and were infected with live C. albicans cells. Western blot and quantitative PCR (qPCR) analyses were performed to confirm that Rab14 knockdown was maintained in the context of eGFP-Rab5 expression (see Fig. S4 in the supplemental material). Live imaging revealed that Rab5 associated transiently with phagosomes containing C. albicans cells as early as <1 min after uptake and that depletion of Rab14 did not affect the kinetics of this recruitment (Fig. 6A). Rab5 dissociated from phagosomes after 3 min, on average, in control and Rab14 siRNA-treated macrophages (Fig. 6B), suggesting that Rab5 localization to phagosomes containing C. albicans cells occurs prior to Rab14 localization and that the retention kinetics of Rab5 is independent of Rab14.
Affiliation: Aberdeen Fungal Group, University of Aberdeen, Aberdeen, United Kingdom.